BRUSSELS—The European Union’s foreign policy chief is estimating that Russia has already amassed 150,000 Russian troops in their biggest military buildup ever near Ukraine’s borders. EU foreign policy chief Josep Borrell declined to say where he got the 150,000 Russian troop figure from but it is bigger than the 110,000 estimate provided by Ukrainian Defense Minister Andriy Taran on April 14. Borrell also said Monday that the condition of imprisoned Russian opposition leader Alexei Navalny was “critical” and that the 27-nation group would hold the Kremlin accountable for his health and safety. Despite the tense developments, Borrell said after a virtual meeting of the EU foreign ministers that, “for the time being, there is no move in the field of more sanctions” to be slapped on Russia. He also said there wasn’t a request for a synchronized EU diplomatic move of expulsions in the standoff between EU member state the Czech …